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More Detail on Risk Urged for a Contraceptive Label

Labels on the popular birth control pills Yaz and Yasmin should be strengthened to include more information about the possibility that the pills could lead to greater risk of blood clots in women, an advisory committee to the Food and Drug Administration said on Thursday.

The panel, which voted 21 to 5 in favor of changing the labels, stopped short of recommending that they warn that the drugs are more likely than other contraceptive pills to cause blood clots. Instead, the experts suggested that the labels note that the evidence about blood clots is conflicting.

Currently, the labels suggest that these contraceptives have blood clot risks similar to those of other birth control pills that combine estrogens and progestins.

Morgan Liscinsky, an F.D.A. spokeswoman, said the panel “definitely felt that stronger labels were needed, that the labels need to be updated to reflect current data and acknowledge that it is conflicting.”

The advisory committee also concluded, by a closer vote of 15 to 11, that the benefits of the pills still outweigh their risks. The F.D.A. does not have to follow the panel’s recommendations, but the agency has indicated concern in recent months as some studies, including its own, have shown an elevated risk.

The question of whether these contraceptives, which use a newer synthetic form of progestin called drospirenone, can make women more prone to blood clots has been a subject of debate. Studies have shown differing results. Bayer, the German company that makes the drugs, has said that they pose no greater threat than other contraceptive pills, all of which somewhat elevate the risk of stroke and blood clots in the legs and lungs.

The company has said that studies that show otherwise contain methodological flaws that undercut the strength of their results.

But other recent research has suggested that drospirenone may somewhat increase the risk of blood clots. An F.D.A. analysis reported that about 10 in 10,000 women taking pills with drospirenone will experience a blood clot or venous thromboembolism in a year, compared with 6 in 10,000 women using other hormonal contraceptives.

And a study of 1.3 million Danish women published in October in the journal BMJ found that women taking Yaz or Yasmin had double the risk of blood clots, compared with women taking the older contraceptives.

Before Thursday’s meeting, an F.D.A. briefing document acknowledged that studies had yielded conflicting results and said new studies were needed. But the scientists recommended that labels on the pills should be changed to inform the public of possible risks.

Although the agency could not determine whether the increased risk resulted from use of the drugs or some other cause, “we believe that, because of the consistency in recent reports for an increased risk, product labeling should reflect that very real possibility,” the scientists wrote.

More than 10,000 lawsuits have been filed against Bayer claiming that women have been harmed by taking Yaz or Yasmin, including accusations of about 100 deaths linked to the contraceptives.

In documents released recently in those lawsuits, David Kessler, a former F.D.A. commissioner working as an expert witness for the plaintiffs, said that Bayer researchers found increased reports of blood clots in women using Yasmin in the United States, compared with those using three other pills, but did not provide that information to the F.D.A. in a 2004 safety review.

“Bayer presented a selective view of the data, and that presentation obscured the potential risks associated with Yasmin,” Dr. Kessler testified. He also said the company promoted the pill for alleviating premenstrual syndrome, when it was not approved for that use.

Dr. Pamela A. Cyrus, a vice president for Bayer HealthCare Pharmaceuticals, said on Thursday that Bayer had consistently worked with the F.D.A. and other regulatory authorities around the world as new data have become available, had worked with the agencies to make label updates as appropriate and “will continue to do so.”

Bayer said it would not comment on Dr. Kessler’s testimony because it is part of continuing litigation.

A version of this article appears in print on December 9, 2011, on page A20 of the New York edition with the headline: More Detail on Risk Urged For a Contraceptive Label. Order Reprints|Today's Paper|Subscribe